How is the best way to make sure Lori spark is bad? I bought a motor and had it installed. it Will idle smooth until the temp go up to normal. I had plugs and new wires installed but it is missing like it has a plug fouled. what else can it be?

 

If you think it is an ignition problem, there is the optispark, coil, ICM, or possibly some bad wiring in between those circuits. If it's not in your ignition system, then you have a long way to go in diagnosis. Fuel system, mechanical damage, other electrical problems, etc.